"We flew by yesterday [Jan. 14], but the first data reports were not in until today. Now we know our instrument has successfully taken the first ion plasma measurements near Mercury ever," said Thomas Zurbuchen of the University of Michigan, who engineered the Fast Imaging Plasma Spectrometer (FIPS) on Messenger. "Now all it takes is patience to wait for the big 70-meter antenna on Messenger to transmit our data back to us."

It will take weeks to receive all the collected data on Mercury's atmosphere, but within two weeks Zurbuchen said his team will have enough samples to get an overall impression of what elements are in Mercury's mysterious atmosphere.

"We should know what the exciting new discoveries are in a couple of weeks, but because this is the first data set of its kind, it is going to be years--perhaps a decade--for follow-up research to explore it all," said Zurbuchen.

Messenger was launched in 2004. This week's fly-by was the first use of FIPS, which was specifically designed to measure the mass of the highly charged particles in the atmosphere of Mercury.

"FIPS looks at all the particles in the atmosphere, of which we expect to see protons and sodium which we can sense from remote observations, but most of the rest of the atmosphere is unknown--our is the first instrument to make real measurements of it," said Zurbuchen.

FIPS gathered some of Mercury's atmosphere as it flew through it at over 15,000 miles per hour. The spectrometer measured the atmospheric elements as the craft grazed past to shed speed before going on to circle the Sun again. Messenger will repeat the maneuver two more times in October 2008 and September 2009 before finally firing its rockets to decelerate into orbit around Mercury in March 2011.

Because Mercury is so close to the Sun, it is bombarded with highly charged particles. FIPS was optimized to measure the mass of solar ions, and performs its analysis of mass using a realtime spectrometer.